Material of the above description, particularly non-woven material currently produced according to conventional non-woven techniques, is generally of a slightly uneven gauge when measurements of thickness are taken across a sample sheet. This is undesirable in many cases, particularly in materials where a precise and even thickness is required, as material not conforming to the desired standard must be discarded. Commonly, in order to provide a certain thickness, the material is heated and pressed to the desired gauge. Material so treated, however, tends to recover slightly after pressing, and as different portions of the sample tend to recover to somewhat different degrees, this leads to a variation in the thickness of the material across the sample. Also, apparatus used in such an operation tends to be very heavy. For example, pairs of solid steel belts are often employed to compress material; the apparatus associated with such belts is required to be large and heavy in order that it might support the weight of the belts.
It is an object of this invention to provide a process for controlling the gauge or thickness of a heat-softenable, sheet material. Such control is intended to provide a product which has a substantially even gauge thickness throughout the sample (low Coefficient of Variation) and also allows the gauge thickness of the final product to be accurately predetermined so that a specific and precise thickness may be set.